Études et publications

Scott JT, Diakhaté M, Vereecken K, Fall A, Diop M, Ly A, De Clercq D, de Vlas SJ, Berkvens D, Kestens L, Gryseels B.

Tropical Medicine and International Health, 2003, 8:100-108 (PMID : 12581433)

In an epidemic focus in northern Senegal, adults had lower intensities of infection than adolescents, a phenomenon that could not be attributed to immunity acquired over the previous 10-15 years of exposure to the parasite because all age groups had had the same number of years' experience of the worm. This article considers whether this pattern could have been because of higher levels of exposure to the parasite in younger age groups. Personal contact with infected water was recorded using a questionnaire in Schistosoma mansoni foci not more than 3 years old and in another, 10-year-old focus. Many aspects of contact (e.g. frequency, duration or time of day of contact) may contribute to the number of encounters with infective cercariae (true exposure), so various assumptions regarding the relationship between water contact and true exposure were tested resulting in a range of exposure indices. People reported a mean of 4.4 separate contacts, and spent a median of 57 min per day in water. Patterns of water contact differed depending on the exposure index used, e.g. considering duration, males spent a longer time in water than females (P < 0.001). But using frequency, females had more contacts with water than males in most villages (P < 0.001). Generally, exposure levels dropped as people become aged (P < 0.001) and residents of the older focus were more exposed than residents of other foci (P < 0.002). Intensity of (re)infection was not related to exposure either alone or in models incorporating age, sex and/or village irrespective of the index used. There is therefore evidence that age, sex and place of residence determine exposure but none to suggest that exposure had an influence on the relationship between these factors and intensity of infection. We propose therefore that in this population other factors have principal importance in determining intensity of infection.

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Chatterjee S, Mbaye A, Van Marck E

Tropical Medicine and International Health, 2003, 8:33-36 (PMID : 12535248)

In recent years, cases of severe morbidity (fibrosis, haematemesis, hepatosplenomegaly, ascites) caused to Schistosoma mansoni infections are on the rise in Northern Senegal. The neuropeptide somatostatin is reported to decrease portal pressure, control variceal bleeding and fibrosis, and reduce Schistosoma-caused clinical morbidity in the rodent model. The aim of this study was to delineate the role of somatostatin in S. mansoni-caused pathogenesis, by studying host levels of somatostatin in the peripheral blood of uninfected and S. mansoni-infected individuals. Subjects from the district dispensary at Richard Toll, in the Medical Region of Saint-Louis, Senegal, infected with S. mansoni and suffering from severe morbidity were selected. A separate group consisted of individuals resident in the same region but uninfected at the time of the study. Significantly lower somatostatin levels were detected in severe morbidity patients, compared with the exposed but uninfected subjects. In patients with schistosomiasis physiological levels of somatostatin may determine disposition of particular individuals towards severe morbidity, as opposed to others. Host pathology can thus be alleviated by the therapeutic ability of somatostatin to treat bleeding oesophageal varices, reduce portal pressure and prevent progression to severe fibrosis.

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Remoue F., Diallo T.O., Angeli V., Hervé M., de Clercq D., Schacht A.M., Charrier N., Capron M., Vercruysse J., Ly A., Capron A., and Riveau G

Trans. R. Soc. Trop. Med. Hyg, 2003, 97 : 361-364 (PMID : )

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Sow S, de Vlas SJ, Mbaye A, Polman K, Gryseels B.

Tropical Medicine and International Health, 2003, 8(8):744-9 (PMID : 12869097)

We evaluated the awareness of and knowledge about intestinal schistosomiasis in a highly infected rural community of northern Senegal where a variety of health information and education activities had taken place for 7 years as a component of different research and control programmes. As the infection had been introduced only recently, an initial 'zero' knowledge can be assumed. Most of the health education activities had been performed with adapted messages through local health and community workers. By a questionnaire, 566 individuals were asked simple questions on symptoms, mode of transmission, the sources of information and health-seeking behaviour. About 86% of the respondents stated that they knew what schistosomiasis was, and 92% that in case of illness they would seek treatment at the health centre. However, only half of the people accurately quoted symptoms associated with intestinal schistosomiasis: diarrhoea, abdominal pain and bloody stools. The majority of respondents realized that the disease was somehow linked with water and (lack of) hygiene, but only 44% of respondents reported water contact as the source of infection. Ultimately, only 30% of the respondents gave adequate answers about both symptoms and mode of transmission. We conclude that even intense and long-lasting education efforts for a specific and straightforward problem as schistosomiasis are not enough to have profound impact on the knowledge of rural traditional communities.

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